<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>Hi All,</div><div><br></div><div>I have been dragging my feet a little on applying George’s relative timing offsets, since the currently the timing constants are all added together and adjusting them for all runs could be exhausting. The following was a suggestion I made to Elton and George a few weeks ago that might be worth discussing at tomorrows meeting:</div><div><br></div><div>=====</div><div><br></div>There are essentially 4 different per channel offsets that have to all be accounted for. <div><br><div><ol class="MailOutline"><li>Align the TDC and ADC to each other (1152 constants) = tdc_adc_relative_offset</li><li>Align the double ended channel to the global time (768 constants) = channel_global_offset</li><li>Relative timing offsets of the ADC/TDCs upstream/downstream (768 constants) = relative_offset == tdiff</li></ol><div><br></div><div>It may be useful if we were to break these all up into their own table. Currently we just store 1152 TDC and 1536 ADC constants. There are also the per-detector base times. It would take a little work, but I might propose the following definition of the times that could break all of this up. </div><div><br></div><div><font face="Courier New">t_adc = (t_adc_raw [ns]) + base_time_offset_adc - channel_global_offset - 0.5 * tdiff * (-1*end) </font></div><div><font face="Courier New">t_tdc = (t_tdc_raw [ns]) + base_time_offset_tdc - tdc_adc_relative_offset - channel_global_offset - 0.5 * tdiff * (-1*end)</font></div><div><br></div><div>where end {0,1} = {upstream, downstream}. This does assume that the same tdiff values are used for the TDC and ADC times. Unfortunately there is still some room for the numbers to interfere. For example, if I change the tdc_adc_relative_offset I might inadvertently change the time difference between the two ends and spoil the global offset. There isn’t any great way I can think of to leave complete flexibility of the values without some constants affecting others. Or at least I should say the <span style="font-family: 'Courier New';">tdc_adc_relative_offset </span>must be fixed before channel_global_offset and tdiff are calculated. </div></div></div><div><br></div><div apple-content-edited="true">
<div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>--</div><div>Michael Staib</div><div>Graduate Student, Dept. of Physics</div><div>Carnegie Mellon University</div><div><a href="mailto:mstaib@cmu.edu">mstaib@cmu.edu</a></div><div>phone: 412-268-2983</div></div></div></div>
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